Tobacco use is the leading cause of preventable disease, disability, and death. Excessive alcohol consumption is the number-three cause of preventable death in the United States. Despite the fact that addiction represents more than 40% of brain-related illnesses, there is a dearth of innovative treatments. Alcohol and nicotine addiction are often treated as separate disorders even though most people with alcohol use disorders also smoke, and continued tobacco use during abstinence from alcohol leads to significantly higher relapse rates. These findings suggest that alcohol and nicotine addictions may develop, and depend on, common pathways. Recently, a large number of human genetic association studies have implicated the neuronal nicotinic receptors (nAChRs), such as the a5 nAChR subunit as playing a critical role in developing alcohol and nicotine dependence processes and recent molecular studies indicate that the a5 nAChR subunit changes the activity of a4b2* nAChRs. Our main objective is to apply a multidisciplinary approach that integrates basic and clinical research to define the molecular basis of the role of nAChRs in ethanol and nicotine consumption and substance use disorders with the goal of generating medications and treatment strategies. In the first part of the project, we will combine behavior and electrophysiology studies and there are two objectives: 1) to characterize the role of the a5* nAChRs in the behavioral effects of ethanol and nicotine and varenicline and 2) to measure the expression and synaptic properties of a4b2* nAChRs responses in dopamine neurons in the ventral tegmental area, a brain region that plays a key role in the reinforcing properties of nicotine and ethanol. These studies have been greatly facilitated by an innovative drinking model we developed that enables ethanol and nicotine to be consumed together without the need for saccharin. In the second part of the project, we will combine clinical studies and genetics to determine whether genetic variants in nAChRs correlate with response to varenicline in a cohort clinically characterized for nicotine dependence and hazardous alcohol use. There are two major objectives: 1) to measure the effectiveness of varenicline, as a treatment for hazardous alcohol use and 2) to genotype the subjects and assess whether polymorphisms in the genes encoding for nAChRs moderate the effect of varenicline to reduce heavy drinking. The linking of genetic analyses with human responses to varenicline will provide a means by which we can measure both the efficacy of varenicline for diminishing alcohol use disorders and to determine whether there are underlying genetic differences in responses to varenicline. Our overall goal is to accelerate the development of more effective medications, and to improve and personalize treatment strategies for substance use disorders. PUBLIC HEALTH RELEVANCE: We have developed a multidisciplinary collaborative research program focused on defining the molecular basis of the role of neuronal nicotinic receptors (nAChRs) in ethanol and nicotine consumption and substance use disorders with the goal of generating medications and treatment strategies. We propose to combine behavior and electrophysiology to define the molecular basis of the role of a5* nAChRs in ethanol and nicotine consumption and determine whether genetic variants in nAChRs correlate with response to varenicline in a cohort clinically characterized for nicotine dependence and hazardous alcohol use. The research garnered from this proposal will facilitate the development of medications that target nAChRs for the treatment of alcohol and substance use disorders.